(Hypothesis?) Did older installs done 'wrong' fail less due to smaller format tiles?

So obviously, there's a lot of ways to do lots of stuff wrong in tiling. I would kind of like some input from people around in the good old/bad old days of tile, basically just to ask if my hypothesis is right/semi-right. I guess I have a few questions about the good old/bad old days of tile as well. This post may be a bit pot stirring, but it's just some ideas I have in my head I'd like to get out, right or wrong.

My hypothesis is this. Tile could be installed, basically, worse, in the "old days" because they were smaller. Large format didn't get widely used until the late 90s or so, correct? I remember at least personally as a kid, all my bathrooms had 2x2 or so octagon tiles on the floor. To me it seems like with smaller tiles, even with using a v-notch and mastic, bonding directly to plywood or drywall with no waterproofing you'd still be getting 80+% or so coverage on the back of the tile and actually bonding it to the surface. And of course, subway tiles with their very tiny 1/16" grout joint didn't allow much water to penetrate the grout. Obviously these installs on bare drywall and plywood are failing now, but seemingly a lot are kicking around for a long time without apparently too crazy amount of water damage or cracked tiles coming up whole/etc. I think compounding this even more, in very old houses with plaster walls, while not impervious to water, it's a lot more essentially waterproof than drywall (I have Structolite I used to practice some plastering on a scrap of Hardibacker that's been outside in a rain storm and is still rock hard...) so people would tile directly on that as well, probably with not that many issues? But then people probably thought plaster and drywall would be interchangeable and they're definitely not.

I'm just kind of thinking the 'old' thinking among many older people was that tiles were essentially waterproof cladding material, and the grout joint was a necessary weakness, but even that was made water resistant by sealer, and the joints are small anyway, and things would be fine if the cladding was just adhered right and there was no voids behind the board it was attached to. I'm not saying this was right thinking, I'm saying this was common thinking. Obviously the modern thinking is build a waterproof structure first, and the tile is decoration after and irrelevant in waterproofing.

I decided in the name of science/laziness, to try an experiment of mastic'd 2x2 grid mosaic sheets on an exterior sanded bare plywood surface that had a plastic lattice that cracked. I knew this was wrong, but I had leftover mastic from a backsplash I did for a friend's family, and the 2x2 grid sheets were $1 each on sale at Lowes, cheaper than said plastic lattice, so I figured "why not?" in the name of science. It's been a few months, and no freezing happened yet, but the grout's not cracked or even discolored (leftover tiny thing of touchup Mapei Keracolor I had that my father gave me...) except at the top, which always happens just because of expansion (there is a small wooden sill above the tiles...) but nothing between the tiles. No cracked grout, no loose tiles, etc. I gave the mastic a long cure time before grouting (a couple of days...) and tried to give the grout a few days to dry without rain. Obviously this is a wrong tile install, and I'm accepting it's wrong and I may have to put a $5-$10 plastic lattice there one day, but I wanted to see essentially, how far wrong you could go before things explode, for lack of better terms. This winter obviously will be a bigger test, and I bet there will be at least some cracked grout/etc, as it gets covered in a foot or more of snow sometimes.

So the basic hypothesis I have is, the reason things seem to fail so often, and so very catastrophically in present times is at least partially because of larger format tiles and just not enough mortar coverage and/or spot bonding/swirls/etc? Could, with even large format tiles, if you got 100% coverage on a flat surface, could the tiles work as cladding as I'm describing as well? As lots of the pictures I've seen/awful work done in my own house by others of spot bonding and not enough coverage and voids, in that context, would even liquid waterproofing membranes and Kerdi/etc be irrelevant at least for occupancy health because even if it's waterproof, there's still tons of stagnant water, water vapor, and eventually mold behind the tile? Could as well, the stagnant water and bacteria/mold even eventually eat said waterproofing membranes? So wouldn't then, it be as important to get full mortar coverage as making a waterproof wall/etc first?

Keep in mind, I'm not advocating not waterproofing (I plan to waterproof very religiously in my own bathroom when I rebuild it...) I'm just kind of wanting to know where the conventional, even if wrong wisdom came from. I mean, eventually the conventional wisdom stopped working, as I'm younger, and most older people in their 60s/etc when I mention tile say "Yeah it's annoying, it always cracks and stuff..." and then you tell them "no no, you just gotta do this and this and this..." and they don't care, and then at the same time, you get advice like grout sealer (which largely seems irrelevant in modern times/by most people on here, and seemingly irrelevant as long as you have 100% mortar coverage and no water gets trapped behind the grout...) for large systemic tile issues from these same people who are otherwise pretty handy people in non-tile related matters.

Also as well, I'd actually like to know some of the history of certain products, like when Redgard, Aquadefense, Hydroban, Durock, etc, came out. I'd like to know the chronology of this sort of thing. I mean, at one point there was wet setting, making thinset from Portland cement, etc? Can anyone shed any light on the good old/bad old days of tile?

Joe there are a lot of layers to your post, and I don't think I could answer every question within it without typing ten times more than what you've posted.

To me the good ol/bad ol days of tile were when mud was your primary preparation for tile. Tile was a trade passed down through apprenticeship, and installer practice varied less because of said method. It did obviously vary, but your options weren't as numerous as they are today for prep and bonding choices.

Mud and tile are a great pair, since tile likes no movement. The sheer mass of the prep almost becomes it's own entity within the structure. It does have limitations though, and without a established method of installation you had variables and methods from each tile guy, still do, but less variables with less choices back then.

The double edge sword created today is by making something more accessible and methods that hinge more on the structures integrity, it opens up more opportunity for failure.

Back then, it was like throwing a basketball in a 7' hoop, you rarely missed, now the hoop is raised and it's easier to miss your shot.

If you can make tile stick with a combination of Portland cement and sand the results were immediate and you were likely a fairly good tile setter. Didn't take but a few failures to make you move on to another calling otherwise. With all the this sticks to anything products out there coupled with a this will make it all right primer, membrane, backer board, or whatever the results of setting tile successfully take more time discover.

The other issue is education. I had 500 hours of classroom and four years field experience before I was allowed to test for journeyman status. Now you can attend a session of three days or less and be "certified". Consumer and marketing wise nobody knows the difference.

I have been doing industry related work the last 20 years having installed tile for 28 years before that. Yes, that is 48 years, amazes me too. When I started doing industry stuff most of the questions were technical. These days the overwhelming amount of questions I receive are how do I successfully sue someone. Every question I have had this week is about pending litigation or a current lawsuit.

In my opinion the tile trade like many others is dumbing down to a scary level.

Well, I don't know about sticking tile to my tongue. That sounds like another Down Under trick. I'm told they don't use tile cutters down there, either. They just crack them over their knee.

I was all about mud back then. Nothing I know of was stuck to plywood or sheetrock, and there was no cement board. If you didn't know how to float mud in every which way you weren't a tile setter, and you didn't get a job.

True, there were no giant tiles, so I don't know how that might have worked out. Biggest thing around when I started was an 8X8. That would have been considered a large format tile.

I'm not sure there was fewer problems in the early days of thin set mortars. Before that tile installations were less common place and being set on mud by artisans were more successful. 40 years ago we had failures, they were just different than today. I do agree that we have less skilled installers and many consumer/handyman installers that do not know all the details needed. Larger tiles need more careful installation. Training is important. I think we hear about more problems, because there is more tile being set and news spreads quickly.

I have been claiming with absolutely no evidence that one reason for building failures including tile failures becoming more prevalent is the general increase in overall tightness of houses. Not so long ago houses leaked enough air that any moisture that got into a wall soon evaporated without issues. Now even a small amount of moisture can be trapped and lead to rot or mold.

It's much easier to get full coverage on a small tile verses today's large format tiles, and that can make a huge difference both while in a shower (moisture pockets) and a floor - gaps can allow it to be cracked easier.

But, as stated, many old installs were on thick mudbeds that tended to float, isolating them from structural movement. Today's installs are much more dependent on a sturdy structure, and the goals seem to be to use thinner materials, plywood isn't as strong or thick as older stuff was because most of the old growth trees are gone. 3/4" ply is no longer 3/4", and then, probably the biggest thing is there are a huge number of people that either don't know, or don't follow the installation instructions. Skill and knowledge takes time, and there really aren't many schools out there teaching the stuff, and few places actually have apprentice programs with any structure these days. Throw in new materials that older installers don't understand, but may use, can lead to those they are trying to tutor using incorrect information.

Ancient tile installs in Europe and the middle east have survived centuries before current material science. Most of them were installed over a bed of sand contained within the walls that could move to isolate the tile from rigid structure.